Re: BUG #10675: alter database set tablespace and unlogged table - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #10675: alter database set tablespace and unlogged table
Date
Msg-id 4065.1404315531@sss.pgh.pa.us
Whole thread Raw
In response to Re: BUG #10675: alter database set tablespace and unlogged table  (Andres Freund <andres@2ndquadrant.com>)
Responses Re: BUG #10675: alter database set tablespace and unlogged table
Re: BUG #10675: alter database set tablespace and unlogged table
List pgsql-bugs
Andres Freund <andres@2ndquadrant.com> writes:
> I think one reason for the separate flag is that the checkpoint
> performed by pg_start_backup/pg_basebackup shouldn't just become more
> expensive because unlogged tables are needlessly flushed to disk. After
> all, unlogged tables are used because normal tables have a too high
> overhead in that scenario.

AFAIK, the "overhead" that unlogged tables are trying to avoid is WAL
I/O.  Nobody has argued (until this thread) that we are worried about
whether checkpoints write them.

            regards, tom lane

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